> Change the original source to something that doesn't need an archive (e.g., a source that was printed on paper), or for which a link to an archive is only a matter of convenience.
As if paper sources are any less susceptible to becoming increasingly unavailable over time...
The archive.today owner made a good suggestion: Wikipedia should make their own archive. They can migrate all archive.xx snapshots there. They have the resources and it would be as resilient as Wikipedia itself.
Since Wikipedia established that the archiver tampered with stored pages I doubt migrating is on the cards, the trust in those archives has been burned regardless of who hosts them going forward.
AFAIK the only evidence of tampered pages are those involved in this controversy. That archive.xx could tamper pages has always been possible (and a reason why Wikipedia should have their own archive, and migrate ASAP).
But still, Wikipedia can corroborate any archive.xx page, and if they find a matching source, archive that instead.